Unit & Data Converters
Length, weight, temperature, currency, time zones and number bases.
Coming soon
The first tools in this category are in development. In the meantime, browse everything that is already live.
About Unit & Data Converters
Unit conversion is the small friction that shows up constantly and never quite becomes automatic. A recipe in grams when your scale reads ounces. A height in feet when the form wants centimetres. A meeting at 3pm in a time zone you have to think about.
These converters handle the standard measurement families — length, weight and mass, temperature, area, volume, speed, and digital storage — along with live currency rates, time zone arithmetic, and the number base conversions developers reach for.
Conversion looks trivial until precision matters. Rounding a value too early can compound into a meaningful error, and some conversions people treat as fixed are not: temperature scales have offsets as well as ratios, and the US and imperial systems disagree about what a gallon or a fluid ounce is. These tools carry full precision through the calculation and only round at the point of display, and they are explicit about which variant of a unit they are using.
Each conversion pair also has its own dedicated page with a reference table, a worked example, and the exact factor used, so you can check the arithmetic or find the value you need without entering anything at all.
The units that are not what you think
A US gallon is about 3.785 litres; an imperial gallon is about 4.546. That is a twenty percent difference hiding behind an identical word, and it propagates into every derived unit — US and imperial pints, quarts and fluid ounces all differ. Recipes, fuel economy figures and container volumes are routinely misconverted because of it.
Weight has a similar trap. An ounce of gold is a troy ounce, roughly 31.1 grams, while an ounce of flour is an avoirdupois ounce, roughly 28.35. Temperature is different again: Celsius and Fahrenheit have both a different scale and a different zero point, so converting a temperature difference is not the same operation as converting a temperature.
Precision and when to round
Rounding early is the most common source of conversion error. Converting 100 kilometres to miles gives 62.137, and rounding that to 62 before multiplying by anything introduces an error that grows with every subsequent step. These converters carry full floating-point precision through the calculation and round only for display.
The corollary is not to report more precision than your input justifies. If you measured something as roughly five feet, converting to 152.4 centimetres implies millimetre accuracy you never had. Match the precision of your answer to the precision of your measurement — a converted figure is never more accurate than the number that went in.
Frequently asked questions
How current are the currency exchange rates?
Rates are fetched from a public exchange rate source and refreshed regularly, which makes them suitable for estimating and comparing. They are indicative mid-market rates, not the rate you will actually receive — banks and payment providers apply their own margin and fees, typically one to four percent, so the amount that lands in your account will differ.
Which gallon, ounce or ton does the converter use?
Each is labelled explicitly, because the ambiguous ones differ substantially. You can choose between US and imperial gallons, fluid ounces, pints and quarts; between troy and avoirdupois ounces; and between metric tonnes, US short tons and imperial long tons. If a unit has more than one common definition, the converter names which one it is applying.
Does the time zone converter handle daylight saving?
Yes. It uses your browser's built-in time zone database, which knows the daylight saving rules for each zone and when they change. This matters when converting a date some weeks out, since the offset between two zones is not constant — regions switch on different dates, and some do not switch at all.
Are conversions done on my device?
Yes, with one exception. All unit, temperature, base and timestamp conversions are pure arithmetic performed locally. The currency converter needs to fetch current exchange rates over the network, but it sends only a request for the rate table — the amounts you enter stay on your device.